Laser spectroscopy

The treatment covers tunable dye lasers; early applications to atomic hydrogen (Doppler-free techniques); the frequency of visible light; quantum beats; detection by ion formation; and opto-galvanic spectroscopy. Doppler-free techniques and their application to the fine structure of hydrogen are seen as important instances of ultrahigh resolution work using highly stabilized lasers and of the contributions of laser spectroscopy to fundamental physics. Measurements of the frequency of visible light leads directly to the fixing of a value for the speed of light and to the declaration that an independent standard of length is no longer necessary. The tunable variety of short-pulse laser extends the bounds of quantum-beat spectroscopy, whereas the combination of ion-detectors with tunable lasers makes it possible to study the very highly excited, bound states and resonant structures above the series limit for atoms in strong magnetic fields.